Polyenes containing unsaturated groups, such as acryloyl groups, react with active hydrogen-containing compounds. Such a reaction is believed to involve an addition of an anion derived from the nucleophilic, active hydrogen-containing compound, acting as a donor, to an activated unsaturated group, which serves as an acceptor. When these active hydrogen-containing compounds are C—H compounds such as malonic ester or acetoacetate, the reaction is known as the Michael addition reaction. It is also known that SH-compounds may function as active hydrogen-containing compounds in a reaction mechanism which is similar to the Michael addition reaction. Such a reaction mechanism with SH-compounds is called a thiolene reaction.
Catalysts for the thiolene reaction include quaternary ammonium compounds, tetramethyl guanidine, diaza-bicyclo-undecene, and diaza-bicyclo-nonene. Thiolene reactions catalyzed by these strong bases are hard to control and have a short pot life. Pot life being defined as the period of time a curable polyene-polythiol mixture remains suitable for application after mixing. Such a composition is non-gelled and has a viscosity sufficient for application as a coating.